Testosterone reduces fat and increases muscle mass in non-obese men aged ≥55 years

Aging is associated with a reduction in testosterone levels in the blood. This reduction causes a number of symptoms, one of which is losing muscle mass.

This small, well-designed 12-month study looked at the effect of the testosterone patch on body composition and hormones in 60 men aged ≥55 years who were healthy and not obese, and who had low-to-normal testosterone levels and typical testosterone deficiency symptoms. Blood testosterone levels increased in patients receiving the testosterone patch and decreased in patients receiving placebo. Fat-free mass and skeletal muscle mass increased in the testosterone group but did not change in the placebo group (Figure). Fat mass decreased with testosterone and increased with placebo; these changes were linked to changes in blood testosterone levels.

The testosterone patch was shown to be safe but one-third of patients left the study early. The main reason for leaving the study was skin irritation.